Waves, sound & optics worksheet with answers

Free printable Waves, sound & optics worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
PI = 3 × 10⁻⁹ W/m²

The sound intensity near a quiet library is 3 × 10⁻⁹ W/m². Find the sound intensity level β in decibels.

I = 3 × 10⁻⁹ W/m²I0 = 10⁻¹² W/m²
β = dB
2.Easy
λ = ?v = 1480 m/sf = 5 kHz

A sound wave in water has a frequency of 5 kHz and travels at 1480 m/s. Find its wavelength λ.

f = 5 kHzv = 1480 m/s
λ = m
3.Medium
S20 m/sOf = 400 Hz

A source of 400 Hz moves at 20 m/s away from a stationary observer. The speed of sound is 343 m/s. Find the frequency f′ that the observer hears.

f = 400 Hzv = 343 m/svs = 20 m/s
f′ = Hz
4.Medium
SO20 m/sf = 600 Hz

An observer moves at 20 m/s towards a stationary source of 600 Hz. The speed of sound is 343 m/s. Find the frequency f′ that the observer hears.

f = 600 Hzv = 343 m/svo = 20 m/s
f′ = Hz
5.Hard
λ = 600 nmd = 0.5 mmL = 1.5 my = ?

Light of wavelength 600 nm falls on two slits 0.5 mm apart. The screen is 1.5 m away. Find the distance y5 from the central bright fringe to bright fringe number 5.

λ = 600 nmd = 0.5 mmL = 1.5 mm = 5
y5 = mm
6.Hard
λ = 656 nmθ1​ = ?

Light of wavelength 656 nm falls at right angles on a grating with 1200 lines per millimetre. Find the angle θ1 of the order-1 maximum.

N = 1200 mm⁻¹λ = 656 nmm = 1
θ1 = °

Answer key

  1. 1. β = 34.77 dB
  2. 2. λ = 0.296 m
  3. 3. f′ = 378 Hz
  4. 4. f′ = 635 Hz
  5. 5. y5 = 9 mm
  6. 6. θ1 = 51.92 °

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